This app was mentioned in 6 comments, with an average of 1.67 upvotes
Speedify does this. It works pretty well for me. Caveats: It's a subscription if you go over 1 GB a month, and it sets up a local VPN, so if you're already using a VPN (i.e. DNS66, AdGuard), you'll have to disable that.
https://play.google.com/store/apps/details?id=com.speedify.speedifyandroid&hl=en_US
Give Speedify a try. It's a VPN that bonds Wi-Fi and 4G. It works well for me. Caveat: As it's a VPN, you can't run other VPNs simultaneously.
https://play.google.com/store/apps/details?id=com.speedify.speedifyandroid&hl=en_US
I have no idea if it works but Speedify claims to do what you're asking.
apps like speedify may help you utilize one or more connections at once.